The expression of arene cis-diols was originally discovered and described by Gibson twenty-three years ago (Gibson, D. T. et al. Biochemistry 1970, 9, 1626). Since that time, use of such arene cis-diols in enantiocontrolled synthesis of oxygenated compounds has gained increasing acceptance by those skilled in the art. Many examples of applications to total synthesis of carbohydrates, cyclitols, and oxygenated alkaloids can be found in the literature, however much of the work done within this area has been with the more traditional approach of attaining optically pure compounds from the carbohydrate chiral pool. (Hanessian, S. in Total Synthesis of Natural Products: The Chiron Approach, 1983, Pergamon Press (Oxford)). Furthermore, none of the work done with these arene cis-diols teaches or suggests the synthesis of the oxygenated compounds which are the subject of the present invention.
In the present invention, unlike in the previous attempts to utilize these arene cis-diols, emphasis has been placed on the application of precise symmetry-based planning to further functionalization of arena cis-diols in enantiodivergent fashion. This approach has previously been successfully applied for the synthesis of cyclitols and sugars. See for example, commonly owned patent applications PCT/US91/02594 (WO91/16290) and PCT/US91/01040, (WO91/72257) the disclosure of which is incorporated herein by reference.
Compounds which can be made by the processes set forth herein include oxygenated compounds, however the present processes are particularly useful for the synthesis of compounds such as D-chiro-inositol 6. This compound is potentially an important pharmaceutical agent for the treatment of diabetes. (See for example: a) Kennington. A. S.; Hill, C. R.; Craig, J.; Bogardus, C.; Raz, I.; Ortmeyer. H. K.; Hansen, B.C.; Romero, G.; Larner, J. New England J. Med. 1990, 323, 373; b) Huang, L. C.; Zhang, L.; Larner. J. FASEB, 1992. A1629, Abstr. #4009; c) Pak, Y.; Huang, L. C.; Larner, J. FASEB, 1992, A1629, Abstr. #4008; Larner, Huang, L. C.; Schwartz, C. F. W.; Oswald, A. S.; Shen, T.-Y.; Kinter, M.; Tang, G.; Zeller, K. Biochem. and Biophys. Commun. 1988, 151, 1416.).
While the therapeutic potential of D-chiro-inositol 6 is immense, its availability is limited. It is currently available from various sources which are not economically feasible for bulk supply of the drug to the pharmaceutical industry. For example, D-chiro-inositol 6 can be obtained as the demethylation product from (+)-Pinitol. (+)-Pinitol can be made from chlorobenzene via a six step synthetic process as previously described in commonly owned application PCT/US91/02594 incorporated herein. In addition (+)-Pinitol can be obtained by the extraction of wood dust. (Anderson, A. B. Ind. and Eng. Chem. 1953, 593). The compound 6 may also be obtained by either cleavage of the natural antibiotic kasugamycin (Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101), or by a possible enzymatic inversion of C-3 of the readily available myo-inositol 8. (Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101.7. Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101).
While these methods for synthesis of D-chiro-inositol 6 have been described they are not optimal for either clinical or bulk supply of the drug candidate.
Specifically, the known methods of synthesis are not amenable to scaleup or are too lengthy. One of the methods involves extraction of pinitol from wood dust (Anderson. A. B. Ind. and Eng. Chem. 1953, 593) and its chemical conversion to D-chiro-inositol. This procedure, applied to ton-scale would use large volumes of solvents and large quantities of other chemicals and would be either impractical or costly or both. The preparation of D-chiro-inositol from the antibiotic kasugamycin (Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101) also suffers from drawbacks because, on a large scale, about half of the acquired mass of product would be committed to waste (the undesired amino sugar portion of kasugamycin), not to mention the expense with the development of the large scale fermentation process for this antibiotic. The inversion of one center in the available and inexpensive myo-inositol can in principle be accomplished enzymatically (Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101.7. Umezawa, H.; Okami, Y.; Hashimoto, T.; Suhara, Y.; Hamada, M. Takeuchi, T. J. Antibiotics (Tokyo) 1965, Ser. A, 18, 101), however no further details on the commercial feasibility of this process have surfaced since 1965.
Based on the shortcomings of the above processes, there is a need for a biocatalytic approach to compound 6 that is an improvement over the above described processes. Such an approach should be environmentally benign as well as amenable to multi-kilogram scale. The currently disclosed process shown in Scheme 1, below is exceedingly brief and efficient in that it provides the epoxydiol 12 in one pot procedure without the necessity of isolation of protected derivative 11. This is an extremely advantageous transformation because it creates four chiral centers in a medium containing water, acetone, magnesium sulfate and manganese dioxide (a naturally occurring mineral), thus making this transformation more efficient and environmentally sound from the point of waste removal. ##STR3## Methods for the synthesis of an epoxydiol 14, which is useful as a synthon, have previously been described (Hudlicky, T.; Price, J. D.; Rulin F.; Tsunoda, T. J. Am. Chem. Soc 1990, 112, 9439) This synthon, which was previously used in the preparation of pinitols, as shown in Scheme 2 below, is now prepared by the controlled oxidation of 11 with potassium permanganate (KMnO.sub.4) and a subsequent dehalogenation to 14 rather than previous methods described by Hudlicky et al., and is useful in the synthesis of various other compounds as shown in Scheme 1. ##STR4##